The present invention relates to an apparatus and method for recording and displaying a three-dimensional image. More particularly, the present invention relates to an apparatus and method which utilizes a phase-conjugate mirror in combination with an emulsion for recording and displaying a three-dimensional image.
In the past, three-dimensional images of an object have been generally recorded by one of two techniques: holography and stereoscopy. In conventional holography, coherent light, usually in the form of a laser beam, is reflected off of the object to be photographed. This reflected laser light and additional laser light from a reference beam are then used to expose a photographic emulsion. The image recorded in the emulsion is not the image of either the reflected laser or the reference laser light alone, but rather a record of the interference pattern formed by the two beams acting upon one another.
One primary disadvantage to holography has been lack of color. Attempts have been made to produce color effect by exposing the same emulsion to the interference patterns formed by lasers at several different frequencies, thereby producing a color image comparable to the color image on a television. However, unless the emulsion is exposed to all frequencies of light, the recorded color is at best an approximation of the true color. Attempts have also been made using white light, i.e., light containing all visible frequencies, but an extremely bright light is usually required and the images tend to be fuzzy.
Another disadvantage of holography is the requirement of dimensional stability between the emulsion, laser, and object which has precluded the use of such systems except in the most esoteric applications.
In stereoscopy, two cameras or a single camera with a split lens are held in spaced alignment with each other. To produce a three-dimensional effect, the developed image through one lens is somehow differentiated from the developed image through the other lens. The three-dimensional movies of the 1950's projected one image in one color and the other image in another color. The viewer then wore spectacles with two different colored lenses to separate the images. Unfortunately, true color is unobtainable using this technique. More recently, in the three-dimensional movies produced in the 1980's, polarization, instead of color, has been used to differentiate the two images. True color is possible using this technique, but the viewer must wear spectacles with lenses having different polarizations. Whether color or polarity is used to distinguish the images, stereoscopy has the disadvantage that the spacing of the cameras must be perfectly maintained and that the viewer must wear typically uncomfortable spectacles to create the three-dimensional effect.
With Lippman photography, fringes or interference fringes are generated when light is reflected by a mercury coating at the back of a special fine grained photographic emulsion; however, this does not provide a three-dimensional image.
Further developments using white light and more simple methods have not been successful in producing three-dimensional images.
The present invention solves these and many other problems associated with recording and displaying a three-dimensional image.